H, W = map(int, input().split())
S = [list(input()) for _ in range(H)]

dx = [0, 1, 0, -1]
dy = [1, 0, -1, 0]

def is_valid(x, y):
    if x < 0 or y < 0 or x >= H or y >= W:
        return False
    return True

def can_draw(x, y):
    for i in range(4):
        nx, ny = x + dx[i], y + dy[i]
        if is_valid(nx, ny) and S[nx][ny] == '#':
            return False
    return True

for i in range(H):
    for j in range(W):
        if S[i][j] == '#' and not can_draw(i, j):
            print('No')
            exit(0)

print('Yes')